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The concrete walls are the downstream walls for Lock #19. And John Weeks III has a nice downstream side view.
Note that the Iowa side is high to clear the barge traffic that uses the lock on the west side of the river. But the Illinois side of the bridge meets the shore below the bottom of the old bridge. Since there is a natural bluff on the Illinois side as well as the Iowa side, if they had made the bridge a little longer and kept the pier heights higher, they could have avoided the flood problems of 1993 and 2008. (I could not find info for 2011 for Keokuk. Was that just a lower Mississippi flood?) During the 1993 flood, the bridge was closed for two weeks before 26000 tons of limestone was piled on the access road and it was opened again. But the speed limit was 5 mph instead of the usual 35 mph. During the two weeks of road closure, a trolley car across the maintenance track on the dam was used by 4000 commuters each day. Even with the low access road in Illinois, this bridge opened sooner after the flood than the bridges at Hannibal, Quincy, and Fort Madison making it the only open bridge in a 230 mile stretch of the Mississippi. In 2008, they learned there lesson in 1993 and piled rock on the road sooner rather than later to keep the road open. A video that shows the water is almost to the bottom of the railroad bridge. A video that shows water on the access road and the bad traffic jams. Skip to timestamp 1:30.
I had noticed that the steel beams for this bridge were huge. And on the Iowa side they are also curved.
The beams are fabricated in the field, and we can see the two joints in the full span.
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